First impressions were poor. There was a talking heads video looping just within the entrance — but audible pretty much throughout the space — which was both unnecessary and distracting. (I'm of the general opinion that authors should be read and not heard.) The space itself is best described as crepuscular. I'm not sure if the low lighting was necessary — there were some old manuscripts on display and I don't even pretend to play an ancient documents expert on the internet — but the lack of illumination became a problem in the furthest corners. I wouldn't complain about the interactive exhibitions — such as the 'design an alien' thing — if only they'd actually served their purpose and kept the kids out from under foot.
As far as the content went, the exhibition's subtitle — Science Fiction but not as you know it — tells you what to expect: if you're an actual SF fan, you won't be surprised to see the whole gamut of the genre, from Swiftian tales of fabulous lands to literary SF by the likes of P.D. James and Kazuo Ishiguro, covered. There are some interesting finds — particularly in the form of early works in languages other than English — but generally it came across as a non-SF fan's idea of surprising SF. ("Some of these books don't have space ships in them! Who knew?")
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So is it worth going to see? In general — and at the price: free — I'd say, "yes". If you strike it lucky and get there when the kids are elsewhere and there are just a smattering of idiots to get in your way, you'll find a lot of interesting items. The original manuscript pages from, among others, Arthur Clarke and J.G. Ballard, complete with corrections in the authors' own hand, are well worth viewing on their own. (I does make me wonder, however, what current authors will be leaving for future exhibitions. In one hundred years time, will crowds gather to view the actual genuine thumb drive China MiĆ©ville had biked to his publisher?) I was also pleased to see that both Iain Banks' Culture and Kim Stanley Robinson's Mars trilogy were given case space.
Final verdict? Take a quick spin around, then buy the accompanying book by Mike Ashley (£16.95 from the gift shop) to enjoy from the comfort of your favourite reading chair.